• Question: what is the average temperature in the brain?

    Asked by italyspilledthepasta~ to Nina on 26 Jun 2019.
    • Photo: Nina Rzechorzek

      Nina Rzechorzek answered on 26 Jun 2019: last edited 26 Jun 2019 9:52 pm

      Thank you for asking! This is THE question that I urgently need to answer – and hope to do so with a brain imaging study.

      We know that brain temperature changes according to time of day (in rodents at least), and that brain temperature changes according to brain region, and in response to brain activity (which can vary by time and brain region), and that brain temperature generally increases with brain injury. For this last bit we do actually have actual human brain temperature data – but the problem is this data may not reflect the temperatures that would exist in the healthy brain. The ‘gold standard’ method of measuring brain temperature is directly, using a temperature probe inserted into the brain – this invasive technique can only be justified in critical care patients (i.e. those with traumatic brain injury, or those who have undergone brain surgery for removing a brain tumour) – FYI these probes measure all sorts of important things in addition to temperature such as brain oxygen levels and pressure within the skull. Whilst these probes can give us lots of data over several days (and so can tell us how brain temperature varies around the clock), the probe will only measure one small point in the brain surface. So to date, the data we have for human brain temperature is limited because it does not tell us about the healthy brain, or different brain regions. From this patient data, ‘average’ human brain temperature looks to be a little higher than the body (brain temperature ranges between about 37 and 40 degrees celsius, whilst body temperature ranges between about 36.5 to 38.5). This is consistent with what has been found in most rodent studies (that brain temperature is a little higher than the rest of the body – which makes sense given the brain accounts for only 2% of our body weight but 20% of our oxygen consumption!)
      Now we have a special brain imaging technique called Magnetic Resonance Spectroscopy (MRS) which we can use to ‘estimate’ brain temperature in a non-invasive way in healthy individuals – this also means we can do this in many different parts of the brain and at different times of day (if we scan peoples’ brains at different times of the day). With this technique we hope to answer your question at least for young, healthy adult men and women – so watch this space! 🙂